The study's subjects received CPR - 36.8 percent received compression-only CPR and 63.2 percent received conventional CPR that included mouth-to-mouth breathing as well compressions -- and automated external defibrillator (AED) shocks from bystanders.

One month later, 46.4 percent of the compression-only CPR patients were alive compared to 39.9 percent of those who received conventional CPR. 40.7 percent of the compression-only patients had favorable brain function compared to 32.9 percent of those who had conventional CPR.

Compression-only CPR, recommended by the American Heart Association, is also preferable because it is easier to learn and to perform without the mouth-to-mouth rescue breathing.

"Across the U.S., too many people are dying from sudden cardiac arrest because family members and friends of the victim are unsure how to help. This study confirms that Hand-Only CPR is highly effective. Plus it's easy to do," said Dr. Michael Sayre, national spokesperson for the American Heart Association and professor of Emergency Medicine at the University of Washington, in a release.

The association still recommends conventional CPR for infants and children who have not yet reached puberty.